Typecasting is easy when it comes to John Medeski and the trio of which he’s been a part for more than two decades, Medeski Martin & Wood. Since their adoption by the jam band crowd after performing with Phish in the mid-’90s, the group — keyboardist Medeski, drummer Billy Martin, and bassist Chris Wood — have sometimes been seen as talented if one-dimensional purveyors of the almighty groove. But the fact is, MM&W have always been experimenters of the first order, exploring a wide dynamic range of moods and world-music styles, always maintaining a strong allegiance to their jazz roots. Charles Mingus, Sun Ra, and electric Miles Davis (of the hugely adventurous pre-1980 years) are typical touchstones covered by the band.

But even knowledgeable MM&W fans might be taken aback by Medeski’s latest project, “A Different Time” — a meditative, low-key solo-acoustic-piano album that includes aWillie Nelson cover and the traditional gospel tune “His Eye Is on the Sparrow.” Released last April, it was the first disc on the revived, legendary Okeh label (on the Sony Masterworks imprint). It’s also Medeski’s firstsolo piano album. In support of the album, he’ll play a solo concert as part of the World Music/CRASHarts program at the Institute of Contemporary Art on Thursday.

“If it’s not what you expected,” Medeski says, on the phone from his home in New York’s Hudson River Valley, “that’s probably subconsciously part of my reason for putting it out.” He laughs and refers to an extremely diverse history of collaborations that includes everyone from John Zorn and Béla Fleck to the Blind Boys of Alabama and Peruvian singer-songwriter Susana Baca.

“I still get pigeonholed into this Medeski Martin & Wood thing,” says Medeski, where his arsenal includes an array of electric keyboards. “Which is me and part of me, and I love it. But I do a lot of different things. Part of my mission was to throw down the gauntlet and say, ‘Hey, we have many sides. This is one side of me.’ ”

Medeski’s eclectic leanings go back to his days at the New England Conservatory in the mid-’80s. Enrolled as a classical piano major, he was playing both classical and jazz in the school’s Third Stream department, which emphasized the importance of moving freely among all genres. He soon decided that life as a classical performer was not for him.

John Medeski

“You start thinking: Who am I really?,” recalls Medeski. “As much as I love Bud Powell and John Coltrane and Albert Ayler and Schoenberg and Beethoven and Messiaen, I also love and grew up with Stevie Wonder and Bob Marley and Sly Stone and Ray Charles. Ray was a big one!” Working with teachers like Ran Blake and Bob Moses, Medeski says, “I started trying to be honest about who I was. And it naturally took me to exploring groove music — and not being afraid.”

Ironically, the new disc takes Medeski back to some of those classical roots. He told producer Henry Hirsch that he wanted the kind of sound and intimacy achieved by one of his idols, classical pianist Arthur Rubinstein, on his iconic RCA Red Seal recordings. Perhaps that’s one reason you can sometimes hear a Chopin-esque harmony in Nelson’s “I’m Falling in Love Again,” or a formal étude-like quality in the darkly dissonant “Ran,” a dedication to teacher Blake.

The other big influence on the session was the piano — a 1924 Parisian Gaveau, a close descendant of the type of piano favored by Chopin. Hirsch had been urging Medeski to try it, and after two nights of recording on the Hirsch studio’s 9-foot Steinway, he did. He found that the Gaveau had an extremely sensitive action. “It requires a lot of control. It gets you into the sound in a different way. You have to really be present or it’s going to sound like a clanker.” He laughs. The piano, he said, “led me in this other direction. It brought out this more reflective and meditative music.”

Not that anyone would necessarily mistake “A Different Time” for a classical record. Nelson’s melody of “I’m Falling in Love Again,” the gospel of “His Eye Is on the Sparrow,” the Randy Newman-esque Americana of Medeski’s “Waiting at the Gate,” and the lovely Latin-tinged waltz ballad “Luz Marina” all make connections with various folk traditions. But the weave of chord voicings throughout, and Medeski’s sensitivity to the instrument’s dynamics — its overtones and dry attack — add another dimension. Just listen to the soft, low rumble beneath the harp-like arpeggios in his original “Graveyard Fields” (named for a rural area in North Carolina).

The piano moved him to try different things. “ ‘Ran’ has been around for seven or eight years. I’d played it maybe one time. That, the Willie Nelson tune, and ‘Waiting at the Gate,’ I never would have played them if it weren’t for the instrument. . . . I love Willie, and I tried to play his tunes before, and it always sounded real schmaltzy on the modern piano. It’s too rich.”

When Medeski listened to the playback of the music, he knew where the heart of his new CD was. “This little set of music [played on the Gaveau] stood out to me as a consistent work on its own.”

Although he says the new record will influence what he plays at the ICA, he won’t be re-creating it — that’s never been his way, or the way of Medeski Martin & Wood. “I’ve never been the kind of musician who makes a record and then goes out and tours the record. To me, that’s more of a pop business paradigm.” And whatever instrument he has on the ICA stage, it most likely will not be a vintage Gaveau. Besides, he says, “I don’t know how exciting a whole night of music would be on the Gaveau.” And like an MM&W show, the ICA set will all depend on mood, audience, the moment. And it won’t be easily pigeonholed.